Help Center/ MapReduce Service/ Component Operation Guide (LTS) (Ankara Region)/ Using Elasticsearch/ Elasticsearch Performance Tuning/ Data Query and Optimization/ Forcibly Merging Segments
Updated on 2024-11-29 GMT+08:00
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Forcibly Merging Segments

Each shard is created based on multiple segments. The decrease of the number of segments can greatly improve the query speed. The index segments can be manually merged periodically to improve the query speed. The batch force merge operation on segments of single index and multiple indexes is supported.

The following is an example of single index in security mode:

curl -XPOST --tlsv1.2 --negotiate -k -u : 'https://ip:httpport/myindex-001/_forcemerge?only_expunge_deletes=false&max_num_segments=1&flush=true&pretty'

The following is an example of multiple indexes in security mode:

curl -XPOST --tlsv1.2 --negotiate -k -u: 'https://ip:httpport/myindex-001, myindex-002/_forcemerge?only_expunge_deletes=false&max_num_segments=1&flush=true&pretty'
curl -XPOST --tlsv1.2 --negotiate -k -u : 'https://ip:httpport/_all/_forcemerge?only_expunge_deletes=false&max_num_segments=1&flush=true&pretty'
  • The force merge operation consumes a large number of disk I/Os. Therefore, you are advised to forcibly merge segments during off-peak hours.
  • max_num_segments: indicates the maximum number of segments. The value 1 indicates that the merge operation is performed until there is only one segment.
  • only_expunge_deletes: Only the segments with the deleted flag are cleared. The recommended value is false.
  • flush: Run the flush command after clearing. The default value is true.